Such a tool is used for fastening an electrical conductor enclosed by an insulation sheath, which conductor can be a single- or multi-core wire, to a contact element, for example a wire end sleeve, a cable lug or a contact socket. By the double crimping tool both an electrically conductive connection between the conductor and the contact element is to be established, and an insulation section adjoining the stripped conductor end is to be fastened to the contact element by a pressing procedure. The crimping tool can be designed as a band tool or as a machine-driven tool.
From U.S. Pat. No. 3,713,322 a crimping tool for connecting a contact to a wire end is known. This tool uses two pairs of press pistons which in guide slots are displaced radially in relation to a receiving cross section so as to press the sleeve positioned in the receiving cross section together with the inserted wire end. In this arrangement initially the first stamp pair with flat anvil surfaces is brought to the contact sleeve in order to press said contact sleeve against an oval shape. During the further crimping process the stamp pair that is positioned across the first stamp pair is brought to the pre-pressed contact sleeve in order to complete the crimping process by curved anvil surfaces. The four press pistons are driven by a shared cam ring, wherein the advance of the individual press stamps is determined by the radially changing surface design on the inside of the cam ring. With this known crimping tool only one crimping process is possible in the region of the stripped end of the cable. Furthermore, during the crimping process a user of the hand tool has to exert considerable forces.
U.S. Pat. No. 5,415,015 shows a crimping tool by which in a single crimping process both in the section of the stripped electrical conductor and in the insulation section a press connection with the contact element to be connected can be established. To this purpose the described manual tool, on two opposing stamps, comprises two differently designed anvil surfaces, situated axially one behind the other, which curing the crimping process act at the same time on the contact region and on the insulation region in order to deform the sleeve-shaped sections of the contact pin. To this effect the press stamps must be matched in a targeted manner to the shape of the contact sleeve. Consequently any processing of different cross sections is largely excluded. Furthermore, with the known crimping tool it is not possible to establish crimping connections that meet stringent safety requirements in the case of permanent strain at the crimp position.
The standard MIL-C-22520/20, dated 19 Mar. 1976, which requires the use of four crimping stamps that contact the circumference of the crimp section, in each case offset by 90°, and that carry out the pressing procedure in pairs, describes the design of a crimp connection that meets such safety requirements and describes the basic design of a tool suitable to achieve this. The requirements of this standard are, for example, met by the crimping tool according to the above-mentioned U.S. Pat. No. 3,713,322. Therefore, when designing a crimping tool that conforms to the standard mentioned, the average person skilled in the art is thus limited in his/her freedom of development so that up to now there was little detectable scope for improvements.
WO 2004/021523 A1 discloses a crimping tool by which the concurrent establishment of a press connection in the section of the stripped conductor end and in the adjacent insulation section is to be made possible. To this effect two crimping units, arranged one behind the other, are provided, each comprising four crimping stamps which during the crimping process at the same time are radially displaced into the receiving cross section where they press the contact sleeve and the conductor together. Concurrent pressing together in the conductor region and in the insulation region requires extremely large forces, in particular at larger cross-sections, which forces can no longer be exerted by a user using a hand tool. The substantial loads encountered result in rapid wear of the press stamps. Furthermore, an unfavourable position displacement of the electrical conductor in the contact sleeve may result when press forces act on the insulation region before the conductor has been adequately fastened in the contact sleeve. Finally, the known crimping tool does not make it possible to process various cross-sections without the individual press stamps being changed.
DE 195 07 347 C1 describes press pliers for wire end sleeves. These press pliers use six press jaws that are swivellably held on bearing pins, and that, when a ring-shaped swivel lever is actuated, are swiveled into the cross section that receives the wire end sleeve in order to carry out the pressing procedure by the resulting reduction in cross section. However, these press pliers do not make it possible to simultaneously produce two crimp connections in axially successive sections and is furthermore not permissible if conductor ends are to be crimped, according to the above-mentioned standard, to wire end sleeves.
From DE 4023 337 C1 a tool for crimping a double connection of a connector with a conductor on the one hand and an insulation on the other hand is known. The tool comprises a tool head that has a frame and a press jaw that is axially affixed to the frame, as well as a press jaw that is axially guided on the frame. The axially guided press jaw comprises at least two stamp plates that have work profiles, and by a drive is pressed against the axially fixed press jaw which in that location comprises at least two anvil plates that have work profiles. At least one of the anvil plates or stamp plates is swivellable, on the respective other anvil plate or stamp plate, on an axis that is arranged so as to be perpendicular in relation to the axis of principal extension so that another edge with a differently designed work profile becomes effective when the jaws are pressed together.
From DE 195 09 442 C2 crimping pliers for the manually actuated fastening of a connector plug to a cable are known, in which four die inserts with several crimp nests are placed onto two opening jaws. The four crimp nests are arranged in the die inserts so as to be placed side by side, of which four crimp nests at least one is arranged such that jamming the tension relief for the cable to be attached to the connector plug takes place on opposite sides of the die inserts. The solution known from this printed publication is, in particular, suitable for crimping connectors to ignition cables.